Risk and the Value of Additional Insecticide Applications for European Corn Borer Control in Processing Sweet Corn

1. Risk and the Value of Additional Insecticide Applications for European Corn Borer Control in Processing Sweet Corn Paul D. Mitchell William D. Hutchison Terrance M. Hurley Midwest Food Processors Association Annual Meeting, St. Paul, MN Dec. 6-7, 2005

2. Overview of Presentation • Goal: use insecticide field trial data to estimate the value and risk effect of an additional insecticide application for ECB control in processing sweet corn • Work in progress as part of NC IPM grant • Preliminary empirical results today

3. Data • Efficacy data from pyrethroid trials (~ 50) • Capture, Warrior, Baythroid, Mustang, Pounce • Most data from: MN, WI, IN and AMT • Data include: • Mean ECB larvae/ear for treated and untreated control plots • % yield marketable for processing • Number of sprays and application rate

4. Empirical Model • Keep key variables random to capture the risk/uncertainty in pest control • Develop hierarchical model of linked conditional probability densities • Estimate non-normal conditional densities • Mean and variance depend on other variables that may be random

5. Random Initial ECB Apply Insecticide Random Remaining ECB Random % Marketable for Processing Random Pest-Free Yield Net Returns Net Returns = PscxYldx%MktProc – PixAIi - #SprysxCostApp - COP

6. Initial/Untreated ECB density • Lognormal density with constant mean and standard deviation • WI DATCP fall surveys of 2nd generation ECB larvae in field corn (1964-2004) • Mean 0.70 • Standard Deviation 0.92 • CV 130%

7. Remaining/Treated ECB density • Lognormal density • Mean and standard deviation functions of initial ECB and amount of applied AI, with insecticide specific effects • More initial ECB, on average more treated ECB • More AI applied, on average fewer treated ECB • Insecticide Specific Effects: at max approved rate, efficacy ranking (best to worst) is: Capture/Warrior-Baythroid, Mustang, Pounce

8. % Marketable for Processing • Beta density between 0 and 1 • Mean function of the ECB larval population density (exponential decrease) • More ECB, on average lower percentage marketable for processing • Constant variance/standard deviation

9. Pest-Free Yield • Harvested yield without ECB damage • Beta density (common for crop yields) • Mean: 6.6 tons/ac (WI NASS 3-yr avg.) • CV: 25% (increase WI NASS state CV) • Minimum: 0 tons/ac • Maximum: 9.9 tons/ac (mean + 2 st. dev.)

10. Prices and Costs • Sweet Corn: $67.60/ton • Insecticides ($/ac-treatment) • Capture Warrior Baythroid $2.82/ac $3.49/ac $6.09/ac • Mustang Pounce $2.80/ac $3.76/ac • Aerial Application: $4.85/ac-treatment • Other Costs of Production: $200/ac • No Cost for ECB Scouting, Farmer Management Time, or Land

11. Model Summary • Stochastic variables: yield, ECB population, insecticide efficacy, % marketable for processing, net returns • Monte Carlo simulations for the hierarchical model • Value with Stochastic Net Returns • Mean/Average/Expected Value Net Returns • Risk with Stochastic Net Returns • Standard Deviation of Net Returns

12. Value of 1st spray: $115-125/ac • 1 Scheduled Spray and use of IPM for 2nd spray maximizes farmer returns

13. Economic Thresholds (ECB larvae/ear) 2nd spray: 0.15 3rd spray: 0.20 4th spray: 0.25

15. Source of IPM value is preventing unneeded sprays • Baythroid and Warrior more costly, so IPM more valuable • After more applications, fewer scheduled sprays needed

17. Summary/Conclusion • First scheduled spray worth $115-$125/ac • 1 scheduled spray and use of IPM for the 2nd spray maximizes farmer returns • Value of IPM vs scheduled additional spray ranges $5-9/ac, not including scouting cost • IPM brings modest reductions in risk • Improvements to make • Specify the processing company’s objective • More representative ECB population data

18. Table 4.Expected net returns ($/ac) for each insecticide use strategy

19. Table 5. Net returns standard deviation ($/ac) for each insecticide use strategy